TECHNICAL INFORMATION
AND
SERVICE DATA
618-T and 721-C
FIVE VALVE, TWO BAND A.C. OPERATED SUPERHETERODYNES
ISSUED BY AMALGAMATED WIRELESS (A/SIA) LTD.
ELECTRICAL SPECIFICATIONS.
FREQUENCY RANGES: Medium Wave ....................................
Short Wave ....................................
INTERMEDIATE FREQUENCY ....................................
POWER SUPPLY RATING 200-260 volts. 50-60 C.P.S. (Instruments available for other voltage and
frequency ratings.)
| POWER CON | ISUMPTION | 60 watts |
|---|---|---|
| DIAL LAMPS |
VALVE COMPLEMENT:
| (I) 6J8GA | Converter | |
|---|---|---|
| (2) 6SK7GT | I.F. Amplifier | |
| (3) 6SQ7GT | Detector, A.F. Amplifier, A.V.C. | |
| (4) 6V6GT | Output | |
| (5) 6X5GT | Rectifier |
I OLIDSPEAKER.
Model 618-T 7 inch—Code No. AY38 Transformer—XA2 V.C. Impedance 3 ohms at 400 C.P.S. Permanent Magnet
Model 721-C 12 inch—Code No. AU44 or AU45 Transformer—TU202 V.C. Impedance 2.2 ohms at 400 C.P.S. Permanent Magnet
UNDISTORTED POWER OUTPUT: 3 watts
MECHANICAL SPECIFICATIONS.
| Height | Width | Depth | |
|---|---|---|---|
| Cabinet Dimensions (inches): | |||
| Model 618-T | 105 | 201 | 87 |
| Model 721-C | 313 | 33 | 12 |
| Chassis Base Dimensions (inches) |
2
|
11 |
5
|
| Carton Dimensions (inches) | - | ||
| Model 618-T | 11 | 20훎 | 11 |
| Model 721-C | 32 | 35 | 133 |
| Weight (nett lbs.): | |||
| Model 618-T | •••• | ||
| Model 721-C | 56 | ||
| Cabinet Finish | Walnut | Vanaar |
CONTROLS MODELS 618-T & 721-C
GENERAL DESCRIPTION.
The models 618-T and 721-C are table and console models respectively. Features of design include: Tropicproof construction, automatic volume control, magnetite cores in I.F. transformers and broadcast oscillator coils, air-dielectric trimming capacitors, straight-line edge lighted
dial. The receivers also incorporate a 200-260 volts, 2-pin power socket to enable either an Electric Clock, F.M. Tuner or Record Player to be connected by means of the 2-pin plug supplied.
|
Part
No. |
XA2
TU202 |
17861A |
AU44 or
AU45 A v 30 |
20507
20354 24261 21938 20007 20052 |
|
|---|---|---|---|---|---|
| Description |
500 uuF Mica (721-C)
8 uF 525 P.V. Electrolytic 0.1 uF Paper, 400 v. working 25 uF 40 P.V. Electrolytic TRANSFORMERS |
Loudspeaker Transformer
(618-T) Loudspeaker Transformer (721-C) Power Transformer |
ou-ou C.F.S.
Power Transformer 40 C.P.S. I AUDSDEAVEDS |
12 inch Permanent Magnet
(721-C) 7 inch Permanent Magnet (418-T) |
Range Switch (618-T)
Range Switch (618-T) Range Switch (618-T) PU/Tone Switch (618-T) PU/Tone Switch (721-C) Power Switch (618-T) Power Switch (721-C) |
|
Code
No. |
C34
C34 C36 C36 C36 C36 C36 C37 C37 C37 C33 C33 C33 C33 C33 C33 C33 |
17 11 | 12 | 888885 | |
|
Part
Description No. |
70 uuF Mica
470 uuF Mica Padder, ± 2½% 12-430 uuF Tuning (618-T) 18211 12-430 uuF Tuning (721-C) 18201 12-430 uuF Tuning (618-T) 18211 12-430 uuF Tuning (721-C) 18201 |
0.1 uF Paper, 400 v. working
70 uuF Mica 70 uuF Mica 0.5 uF Paper, 200 v. working 0.1 uF Paper, 400 v. working |
9 uuF Mica
70 uuF Mica 100 uuF Mica |
200 uuF Mica
100 uuF Mica 0.01 uF Paper, 600 v. working 50 uuF Mica |
0.01 UF Paper, 600 v. working
0.02 UF Paper, 600 v. working 0.01 UF Paper, 600 v. working (618.7) 0.0025 UF Paper, 600 v. working (721-C) 16 UF 525 P.V. Electrolytic 200 uvF Mica (618-71) |
|
Code
No. |
CI6
CI7 CCI8 CCI9 CCI9 CCI9 CCI9 CCI9 CCI9 CCI6 CCI6 |
C22
C23 C23 C24 |
C25
C27 C28 C28 C27 C28 C27 C28 C28 C28 C28 C28 C28 C28 C28 C28 C28 |
C3
C3 C3 C3 C3 C3 C3 C3 C3 C3 C3 C3 C3 C |
|
|
Code Part
No. Description No. |
kl 2 0.5 megohm—Volume Control, |
817 50,000 ohms, Ĩ watt
818 50 ohms, 3 watt 819 100 ohms, ½ watt 220 100 ohms, ½ watt 221 0.25 megohm, 1 watt |
cz2 1.0 megonm, 1 watt |
CAPACILORS
21 4 uuF Mica 22 3-25 uuF Air Trimmer 23 0.05 uF Paper, 200 v. working |
25 9 uUF Silvered Mica
25 9 uF Mica Firimmer 26 3.25 uLF Air Trimmer 27 0.1 uF Paper, 200 v. working 28 3.25 uUF Air Trimmer 28 3.25 uUF Air Trimmer 29 3.25 uUF Air Trimmer 210 4000 uUF Mica Padder, ± 2½% 211 0.05 uF Paper, 400 v. working |
| t . | 0000 | 0000000 | |||
|
Pc
escription N. |
UCTORS
Including C4) 938 540-1600 Kc/s 1545 6-18 Mc/s 1545 |
oil, 570-100 N/S 1545
oil, 6-18 Mc/s 1545 ansformer 2270 ansformer 2270 |
ESISIORS
½ watt 1s, ½ watt |
s, I watt
s, 2 watt 1s, ½ watt 1s, ½ watt |
CIRCUIT CODE-RADIOLAS 618-T & 721-C.
CHASSIS UNDERNEATH VIEW MODELS 618-T/721-C
SOCKET VOLTAGES.
| Valve | Co |
ithode to
Chassis Volts |
0 |
Screen Gr
to Chassi Volts |
id
s |
Anode to
Chassis Volts |
Anode
Current mA |
Heater
Volts |
|
|---|---|---|---|---|---|---|---|---|---|
| 6J8GA Converter: M.W. | 1.5 | 80 | 240 | 1.0 |
6.3 |
||||
| S.W. | 2.0 | 80 | 240 | 1.3 | 6.3 | ||||
| Oscillator: M.W. | 115 | 5.0 | |||||||
| S.W. | 115 | 5.0 | |||||||
| 6SK7GT I.F. Amplifier | 0 | 80 | 240 | 5.0 | 6.3 | ||||
| 6SQ7GT 2nd Det., A.V.C. A.F. Amp. | 0 | 90* | 0.6 | 6.3 | |||||
| 6V6GT Output | 13 | 240 | 225 | 40.0 | 6.3 | ||||
| 6X5GT Rectifier | 300 | · | 280 (A.C.) | 6.3 |
Volts across back-bias resistor R18-3.0.
Total H.T. Current—60 mA. Measured at 240 volts A.C. supply. No signal input. Volume control maximum clockwise. Voltmeter 1000 ohms per volt; measurements taken on highest scale giving accurate readable deflection.
*This reading may vary depending on the resistance of the voltmeter used.
| Winding |
D.C. Resistance
in ohms |
|---|---|
|
Aerial Coil (M.W.):
Primary (L2) Secondary (L3) |
30
4 |
|
Aerial Coil (S.W.):
Primary (L4) Secondary (L5) |
4
★ |
|
Oscillator Coil (M.W.):
Primary (L6) Secondary (L7) |
2
6 |
|
Oscillator Coil (S.W.):
Primary (L8) Secondary (L9) |
* |
|
I.F. Transformer Windings
I.F. Filter (L1) |
10
17.5† |
|
>
ower Transformer (T2):
Primary Secondary |
50
|
|
Loudspeaker Input Transformer (TI):
XA2 Primary XA2 Secondary TU202 Primary |
450
* |
| TU202 Secondary | * |
D.C. RESISTANCE OF WINDINGS.
The above readings were taken on a standard chassis, but substitution of materials during manufacture may cause variations, and it should not be assumed that a component is faulty if a slightly different reading is obtained.
*Less than I ohm.
tless than 1 onm. In some receivers this reading may be as high as 60 ohms.
MECHANICAL REPLACEMENT PARTS
| ltem | Part No. | ltem | Part No. |
|---|---|---|---|
| Cabinet: Model 618-T | C89 | Dial, pointer assembly: Model 618-T | 20522 |
| Model 721-C | C86 | Model 721-C | 20331 |
| Cable, aerial | 15452 | Dial, scale: Model 618-T | 23340 |
| Cable, power: Model 618-T | 23926 | Model 721-C | 23342 |
| Model 721-C | 24605 | Drum, drive: Model 618-T | 2013 0 |
| Cable, speaker | 19188 | Model 721-C | 15684 |
| Cable, volume: Model 618-T | 20425 | Knob | 4589 |
| Model 721-C | 20416 | Socket, valve | 4704 |
| Chassis, end: | Socket, valve cushion | 20142 | |
| Model 618-T—Left hand | 24240 | Spindle, assembly, drive: | |
| Right hand | 22417 | Model 618-T | 20505 |
| Model 721-C—Left hand | 24241 | Model 721-C | 20339 |
| Right hand | 20316 | Strip, tag: I way | 7628 |
| Clip, grid | 7459 | 2 way | 8863 |
| Dial, frame assembly: Model 618-T | 20514 | 3 way | 8821 |
| Model 721-C | 2034 3 G | Terminal, spring | 5458 |
ALIGNMENT PROCEDURE.
Manufacturer's Setting of Adjustments.
The receiver is tested by the manufacturer with precision instruments and all adjusting screws are sealed. Realignment should be necessary only when components in tuned circuits are repaired or replaced or when it is found that the seals over the adjusting screws have been broken.
It is especially important that the adjustments should not be altered unless in association with the correct testing instruments listed below.
Under no circumstances should the plates of the ganged tuning capacitor be bent, as the unit is accurately aligned during manufacture and cannot be readjusted unless by skilled operators using specialised equipment.
For all alignment operations, connect the "low" side of the signal generator to the receiver chassis, and keep the generator output as low as possible to avoid A.V.C. action.
Also, keep the volume control in the maximum clockwise position
Testing Instruments.
- (1) A.W.A. Junior Signal Generator, type 2R3911, or
- (2) A.W.A. Modulated Oscillator, type J6726. If the modulated oscillator is used, connect a 0.25 megohm non-inductive resistor across the output terminals, and, for short wave alignment, an additional 400 ohms non-inductive resistor in series with the "high" output lead of the instrument.
- (3) A.W.A. Output lead of the instrument.
| Order | Connect "high" side | Tune Generator | Tune Receiver | Adjust for maximum | |||
|---|---|---|---|---|---|---|---|
| of Generator to: | to: | Dial to: | peak output | ||||
| | | 6J8GA* | 455 Kc/s | 540 Kc/s | LI3 Core | |||
| 2 | 6J8GA* | 455 Kc/s | 540 Kc/s | LI2 Core | |||
| 3 | 6J8GA* | 455 Kc/s | 540 Kc/s | LII Core | |||
| 4 | 6J8GA* | 455 Kc/s | 540 Kc/s | LI0 Core | |||
| Repeat the above adjustments until the maximum output is obtained. | |||||||
| 5 | Aerial Terminal | 600 Kc/s | 600 Kc/s | L.F. Osc. Core Adj. (L7)† | |||
| 6 | Aerial Terminal | 1500 Kc/s | 1500 Kc/s | H.F. Osc. Adj. (C8) | |||
| 7 | Aerial Terminal | 1500 Kc/s | 1500 Kc/s | H.F. Aer. Adj. (C2) | |||
| Repeat adjustments 5, 6 and 7. | |||||||
| 8 | Aerial Terminal | 16 Mc/s | 16 Mc/s | H.F. Osc. Adj. (C9)‡ | |||
| 9 | Aerial Terminal | 16 Mc/s | 16 Mc/s | H.F. Aer. Adj. (C6)§ | |||
ALIGNMENT TABLE.
*With grid clip connected. A 0.001 uF capacitor should be connected in series with the "high" side of the test instrument. †Rock the tuning control back and forth through the signal. ‡Use minimum capacity peak if two can be obtained. Check to determine that the trimmer has been adjusted to correct
Use minimum capacity peak if two can be obtained. Check to determine that the trimmer has been adjusted to correct peak by tuning the receiver to approximately 15.09 Mc/s. where a weaker signal should be received.
SUse maximum capacity peak if two can be obtained.
CONNECTION TO POWER SUPPLY.
The receiver should not be connected to any circuit supplying other than alternating current from 200-260 volts and at the frequency stated on the label within the cabinet. The power supply connections are shown in the accompanying diagram.
CHASSIS REMOVAL.
Model 618-T.
- (1) Remove the control knobs—each is held by a setscrew.
- Disconnect the cable from the loudspeaker.
- (3) The chassis is held in the cabinet by two screws. Remove these and withdraw the chassis.
Model 721-C.
- (1) Remove the control knobs—each knob is held by a set-screw.
- (2) Disconnect the cable from the loudspeaker.
- (3) The chassis is held in the cabinet by four winged nuts, two at each end of the dial frame assembly. Removal of these enables the chassis to be withdrawn.
RED DOT INDICATES COMMON CONNECTION FOR ALL VOLTAGES
DIAL POINTER ADJUSTMENT
The dial pointer is held in position by two rubber-lined clips. To alter the position of the pointer, loosen the two holding clips slightly and move the pointer in the required direction. It is important to reclamp the clips after any adjustment of the dial pointer.
DRIVE CORD REPLACEMENT.
Follow the diagram which is affixed to the back of the dial frame assembly. This shows the route of the cord and the method of attachment.
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